Introducing Gill’s mealybug, Ferrisia gilli (Hemiptera: Pseudococcidae), an emerging pest of California Sierra foothill wine grapes

The seasonal biology of Gill’s mealybug ,Ferrisia gilli Gullan, a new pest of California wine grapes in the Sierra foothill region, was studied in six Sierra foothill vineyards. Ten untreated vines in each vineyard were non-destructively sampled bi-weekly to determine the location of the mealybugs, their age structure and density. Each vine was divided into seven sections – trunk base, trunk, armpit and under cordon, old spur, new spur, leaf, and grape cluster-and each section was searched for 3 minutes on each sample date. In addition, 20 vines in one-acre plots were destructively sampled (bark was peeled and leaves and clusters removed when appropriate) on each sample date and mealybug age structure and densities recorded. Mummified mealybugs were collected when found and generalist natural enemies recorded. Near harvest, mealybug densities within clusters was recorded and cluster damage ratings were made.